1. Field of the Invention
The present invention relates generally to the field of laboratory ware, and more particularly to flasks useful for various types of culture such as cells, tissues, and micro-organisms.
2. Technical Background
The use of culture flasks to grow or culture cells, tissues, and the like has been long practiced. A typical culture flask is made of a clear plastic structure, having a cylindrical, rectangular, or square body and a removable cap closing off a neck opening.
Harvesting of material from the flasks has traditionally been accomplished by the addition of a chemical additive, such as trypsin, to the flask in order to release the cells from the flask walls. The cells are then typically harvested from the flask through the neck opening. To facilitate removal of material from the flasks, various features have been developed including inclined ramps between the neck and growing surface and specially formed necks which allow cell scrapers to reach all the corners of the growing surface. While these features make use of the flasks somewhat more convenient, it nevertheless remains difficult to remove material from the growing surface, particularly when only selected areas are to be removed for analysis, and it is essentially impossible to remove large sections of monolayers of cells through the neck.
Various flask designs have been developed which attempt to ease gaining access to the flask interior in order to remove selected areas of the cultures or to remove large layers of cells. Some designs utilize weakened or thinner flask areas which may be broken away or more easily cut by an electric iron or other cutting tool. These arrangements have many disadvantages, the most obvious of which are the possibility of culture contamination by chips of flask material falling into the culture when the flask is cut and damage to the culture by the heat and fumes generated from melting the flask with an electric iron. Other designs have tried to avoid those disadvantages by including flask walls or sections of flask walls which are flexible, held in place by adhesive or heat sealing, and able to be peeled away from the flask body. Although minimizing the disadvantages of the previous designs, these arrangements have their own shortcomings such as possible culture contamination from contact with the adhesive, a weaker overall flask structure from lessened support from the flexible wall section, and possible puncturing of the flask body through the flexible wall section.